A conventional ignition apparatus is known which includes an ignition coil equipped with a primary coil and a secondary coil and a spark plug connected to the secondary coil, and works to supply energy to the spark plug by means of electromagnetic induction arising from energization and deenergization of the primary coil, thereby creating spark discharges.
In the known conventional ignition apparatus, the amount of energy inputted to the spark plug depends directly on specifications of the ignition coil. This may cause an excessive amount of energy to be supplied to the spark plug depending upon operating conditions. The direct dependence of the energy input amount, therefore, contributes to increased consumption of fuel.
Ignition apparatuses which are capable of variably changing the energy input amount to improve the fuel consumption are, therefore, sought.
Japanese Patent No. 3791364 teaches an ignition timing control apparatus as described below.
The ignition timing control apparatus works to increase an advance angle limiter which limits a maximum value of an ignition timing advance angle in a transient period including start of an internal combustion engine to be greater than that in a non-transient period in order to ensure a required amount of ignition energy. The ignition timing control apparatus is, however, designed to determine the energy input amount depending upon the specifications of the ignition coil, which is thought of as contributing less to the improvement of fuel consumption.